Noroviruses are estimated to be responsible for two-thirds of the non-bacterial food-borne illness and nearly all (96%) of the non-bacterial gastrointestinal illnesses each year in the United States. Norovirus infection occurs via the fecal-oral route from contaminated food such as oysters (Berg et al., 2000, J. Infect. Dis., 181:S381-S386; Shieh et al., 2000, J. Infect. Dis., 181: S360-S366), water (Yoder et al., 2004, Morb. Mortal. Wkly. Rep., 53(SS-8): 1-15; Blackburn et al., 2004, Morb Mortal Wkly Rep, 53(SS-8): 23-39) and even bakery products (Deneen et al., 2000, J. Infect. Dis., 181: S281-S283). Infections also occur by droplet transmission, contact with contaminated fomites, or person-to-person transmission in contained or semi-contained areas such as cruise ships (Center for Disease Control and Prevention, 2002, Morb. Mortal. Wkly. Rep., 51(49): 1112-1115), hospitals, nursing homes, restaurants, and schools (Gallimore et al., 2004, J. Clin. Microbiol., 42: 1396-1401).
Noroviruses can not be propagated by cell culture techniques. However, Noroviruses are now detectable by various Reverse Transcription Polymerase Chain Reaction (RT-PCR) techniques. Real-time RT-PCR assays have been developed using either SYBR® Green and TaqMan® style assays for the detection and subsequent quantification of these viruses (Donaldson et al., 2002, Water Res., 36: 2505-2514; Kageyama et al., 2003, J. Clin. Microbiol., 41: 1548-1557; Kojima et al., 2002, J. Virol. Methods, 100: 107-114; Richards et al., 2004, J. Virol. Methods, 116: 63-70). SYBR® green assays, while useful for detection, are not reliable in quantification of template concentration due to its non-specific intercalation into any double stranded DNA (primer-dimer and products of non-specific amplification). There remains a need for methods and reagents that can detect or quantify more than one type of Norovirus and/or Enterovirus in a reaction mixture.